I am frequently asked when a handwritten thank you note should be sent vs. an e-mail thank you note. My answer is very simple, always.
If someone has taken time to go out of their way to do something special for you, they deserve a handwritten thank you note. Certainly, an e-mail thank you gets the message across quickly. However, the handwritten note adds a special touch.
This is very similar to a handshake. Do you want to receive a warm sincere handshake or will the soft, wimpy, get it over with style do?